This application relates to a bracket for attaching liners to the convergent flaps and seals which are part of a convergent/divergent nozzle for a gas turbine engine, and wherein the bracket connections are more thermally compliant than in the prior art.
A gas turbine engine typically includes a plurality of sections, which are positioned in series. A fan section moves air downstream towards a compressor section. The compressor section compresses the air and delivers it into a combustion section. In the combustion section, air and fuel are mixed and combusted. Products of combustion pass downstream over turbines, and then outwardly through a nozzle.
It is known in the prior art to vary the cross-sectional area of the nozzle by having flaps that pivot inwardly and outwardly. Typically, a plurality of circumferentially spaced flaps and seals are positioned upstream of a throat, and are called the convergent flaps and seals. Downstream of the throat are divergent flaps and seals. The convergent flaps and seals not only move to define the throat area, but they also provide a block for the products of combustion reaching a housing outboard of the flaps and seals.
In the convergent flaps and seals, a liner typically faces the products of combustion. The liner is connected by a bracket to the flap or seal. Traditionally, the bracket has been welded to the hot liner. The bracket is then bolted to the cooler flap or seal.
In the prior art, the brackets have proved challenging to mount to the hot liner. In particular, the liner extends over a portion of the length of the nozzle, and as one moves downstream in the nozzle, the liner is subject to greater heat. The net effect is that the liner will tend to approach gas path temperatures, whereas the bracket will tend to approach the cooler temperature of the cooling air.
At any rate, the bracket is subject to a thermal gradient along the length of its connection to the hot liner. The bracket has been welded along its entire length to the hot sheet. This provides a relatively rigid connection which is not able to adjust to thermal gradiations. In the prior art, very thermally resistant materials (having a low coefficient of thermal expansion) have been utilized for the bracket and the hot plate. However, this sometimes proves to be an undesirable constraint.
Rivet connections are known, wherein there is clearance provided between the rivet and the surfaces being held by the rivet. This clearance allows some relative expansion between the various components to allow for thermal gradiation. Such connections have not been utilized, however, in the nozzle and, more particularly, to connect a bracket to a liner.